Peristaltic infusion device drip chamber yoke

ABSTRACT

A rotary type of peristaltic pump having the rotor member mounted on one side thereof and including a swing arm rotatably mounted along the side of the peristaltic pump such that the swing arm is movable between a fluid delivery set loading open position and a closed position which automatically aligns and stretches a portion of the fluid delivery set around the rotor member to ensure that the fluid delivery set is properly aligned about the rotor member of the peristaltic pump. A charger unit assembly is disclosed which is particularly adapted to receive the peristaltic pump thereon for charging the batteries of the peristaltic pump; to provide power to the peristaltic pump and for mounting the peristaltic pump on a support pole. The peristaltic pump also includes drip chamber yoke assembly consisting of a pair of outwardly extending members which receive the drip chamber of the fluid delivery set therein. These members are spaced apart a predetermined distance so that if the length of the drip chamber is less than the predetermined distance, the drip chamber will be supported by the top member. If the length of the drip chamber is greater than the predetermined distance, the drip chamber will be supported by the bottom member.

This is a divisional of copending application Ser. No. 07/538,791 filedon Jun. 15, 1990, now U.S. Pat. No. 5,057,081.

FIELD OF THE INVENTION

The present invention relates to an infusion device for introducingmedical fluid into the body of a patient at a controlled rate and moreparticularly to an infusion device having a swing arm particularlyadapted to facilitate the insertion and loading of a resilientlycompressible fluid delivery set about the rotor of a peristalticinfusion device.

BACKGROUND OF THE INVENTION

The present invention is adaptable for use on nearly any medicalinfusion device wherein medical fluids are delivered to the patientthrough a flexible tubing such that none of the medical fluid comes intodirect physical contact with the components of the infusion device. Onewell known group of infusion devices used in the medical industry areperistaltic pumps. Peristaltic pumps are used in combination withdisposable fluid delivery sets or cassettes. Fluid delivery setsgenerally consist of a cylindrical drip chamber assembly, which isconnected to an inlet tube at one end and a resilient and stretchablesilicone tube on the other end; a mounting member connected to thesecond end of the silicone tube and an outlet tube connected between themounting member and the patient.

Peristaltic pumps are generally classified as being either a rotaryperistaltic pump or a linear peristaltic pump. U.S. Pat. No. 4,913,703granted to Pasqualucci et al discloses a rotary type of peristaltic pumpand U.S. Pat. No. 4,493,706 granted to Borsanyi et al discloses a lineartype of peristaltic pump, both of which are incorporated herein byreference. Rotary peristaltic pumps commonly include a motor drivenrotor mounted on the front surface of the pump. The rotor carries two ormore circumferentially spaced apart rollers which are designed toreceive the silicone tube of the fluid delivery set mounted thereon. Asthe motor rotates the rotor, the spaced apart rollers are sequentiallybrought into contact with the silicone tube to compress portions of thesilicone tube. A predetermined volume of medical fluid is containedbetween the compressed portions of the silicone tube so that apredetermined volume of medical fluid is advanced through the siliconetube as the rotor is rotated by the motor. Because the volume of medicalfluid contained between the compressed portions of the silicone tube isa known quantity, the amount of fluid to be delivered to the patient maybe regulated by controlling the rate of rotation of the rotor by themotor.

In many of the commonly available rotary peristaltic pumps, the fluiddelivery set is mounted in a pair of recesses located on the frontsurface of the pump such that the drip chamber assembly is received inthe first recess and the mounting member is received in the secondrecess. Once the drip chamber assembly and mounting member have beenplaced in the respective recesses, the silicone tube must then bestretched to position the silicone tube around the rotor of theperistaltic pump so that portions of the silicone tube are compressed bythe rollers on the rotor. When the silicone tube is stretched around therotor of the peristaltic pump, the silicone tube has a predeterminedlength and internal diameter.

In an effort to facilitate the mounting of the fluid delivery set on thetypical peristaltic pump, the rotor is typically positioned on the frontsurface of the peristaltic pump so that the entire rotor is exposed.During normal movement of the peristaltic pump from a storage area to apatient's room or during ambulatory use, the peristaltic pump may beaccidentally dropped or the rotor of the peristaltic pump mayaccidentally contact the hospital bed or another object. Although therotor on the typical peristaltic pump is designed to withstand much ofthe usual contact which occurs in a hospital, the shaft which connectsthe rotor to the motor may be damaged. Even though the peristaltic pumpmay continue to operate, the increased resistance caused by the damagedshaft may dramatically decrease the operating life of the motor orcreate an inaccurate delivery rate.

Because the fluid delivery set is typically changed every day, it isimportant that the fluid delivery set is manufactured according tofairly rigid manufacturing specifications. The silicone tube of thefluid delivery set is selected so that the internal diameter of thesilicone tube will be consistent for each fluid delivery set when thesilicone tube is stretched and positioned around the rotor. Oftentimes,the length and diameter of the drip chamber assembly will vary betweendifferent manufacturing lots. Because the drip chamber assembly istypically mounted on the peristaltic pump by inserting the bottom end ofthe drip chamber assembly into a first recess, the top end of the dripchamber assembly may not be properly aligned with the drop sensors onthe peristaltic pump. This may result in an incorrect reading of thefluid drops by the drop sensors so that the drop sensors on theperistaltic pump may indicate that there is a flow error andautomatically disconnect the motor on the peristaltic pump.

With many of the commercially available peristaltic pumps, the fluiddelivery set may be improperly mounted the rotor if the drip chamberassembly and/or the mounting members are improperly positioned in therespective recesses. With certain peristaltic pump designs, it is alsopossible for the silicone tube to fall off the rollers of the rotor ifthe patient accidentally displaces the mounting member or drip chamberassembly from the respective recess during operation of the peristalticpump. In these situations, it is possible to have an uncontrolled flowof medical fluid to the patient because the rollers of the rotor are notproperly compressing the silicone tube to restrict the flow of fluidthrough the fluid delivery set. If the peristaltic pump is being used todeliver enternal fluid to a patient, the uncontrolled infusion ofenteral fluid to the patient may result in aspiration of the fluid intothe patient's lungs or over infusion of the enteral fluid.

At present, only one commercially available peristaltic pump includes asafety mechanism to detect the improper mounting of the fluid deliveryset on the peristaltic pump. This safety mechanism is disclosed in U.S.Pat. No. 4,913,703 which is assigned to the assignee of the presentinvention, Sherwood Medical Company. As disclosed in U.S. Pat. No.4,913,703, the operation of the pump motor is prevented when the fluiddelivery set is not detected by the peristaltic pump. Additionally, analarm will sound if the user attempts to operate the peristaltic pump ifthe fluid delivery set is not properly mounted on the peristaltic pump.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide aninfusion device which is designed to overcome the problems describedabove and prevent the improper mounting of the fluid delivery set on theinfusion device.

It is another object of the present invention to provide an infusiondevice wherein the fluid delivery set may be quickly and accuratelymounted about the rotor of the infusion device.

Another object of the present invention to provide a compact infusiondevice with a side mounted rotor and swing arm so that the fluiddelivery set may be loaded or removed from the infusion device by anurse or an ambulatory patient.

A further object of the present invention is to provide an infusiondevice with a swing arm which receives the fluid delivery set in an openposition and which properly orients the fluid delivery set around therotor of the infusion device when the swing arm is moved to the closedposition.

A further object of the present invention is to provide a charger unitwhich is readily mountable on the peristaltic pump to recharge thebatteries of the peristaltic pump and/or support the peristaltic pumpfrom a support pole.

One form of the present invention is described hereinafter withparticular reference to a rotary peristaltic pump particularly adaptedfor the infusion of enteral fluids to a patient, however, it should beunderstood that the present invention may be used on nearly any type oflinear or rotary infusion device where it is desirable to ensure that afluid delivery set is properly mounted on the infusion device to deliverfluid at a controlled rate.

As described more fully hereinafter, the preferred form of the presentinvention includes a housing assembly having a rotary member extendingfrom one side thereof. The housing assembly further includes aprotective covering for the rotary member and a first channel with aplurality of projections and recesses thereon to receive the dripchamber assembly of the fluid delivery set therein. A swing arm on thepresent invention is operatively mounted on the housing assembly of theperistaltic pump. The swing arm is designed to rotate about the side ofthe housing assembly between an open first position and a closed secondposition. In the open position, the swing arm extends downwardly andforwardly from the housing assembly to allow the relaxed fluid deliveryset to be readily loaded into the first channel on the housing assemblyand a second channel on the swing arm. Once the fluid delivery set isloaded into the housing assembly and swing arm, the swing arm may berotated to the closed position so that the fluid delivery set isoperationally positioned on the peristaltic pump with the silicone tubestretched and properly oriented about the rollers on the rotor of theperistaltic pump.

Once the swing arm is moved to the closed position, the inlet tube onthe fluid delivery set extends upwardly from a forward opening at thetop of the housing assembly and the outlet tube extends upwardly from arear opening at the top of the housing assembly. A plurality of openingsare formed on the side of the housing assembly to allow the user tovisually observe the flow of fluid through the drip chamber assembly andthe outlet tube. Additionally, the bottom end of the housing assembly isopen to allow the user to observe the operation of the rotor.

A rotor shield is positioned along the side of the housing assembly toprotect the rotor and shaft of the present invention from damage causedby accidental contact with an object during movement of the peristalticpump. Additionally, the present invention includes a drip chamber yoketo align the drip chamber assembly with the optical path of the dropsensors on the housing assembly.

The front surface of the housing assembly includes a control panel andan alpha numeric LED display panel which signals the user when there isa flow error, low battery, system error or when the fluid delivery setis improperly mounted on the peristaltic pump. The motor and electricalcircuitry of the present invention are contained within the housingassembly. The rear and bottom surfaces of the housing assembly include aplurality of slots or grooves therein to enable the present invention tobe mounted on a charging unit and/or on a support pole when the presentinvention is used at bedside in a hospital.

An advantage of the present invention is that it is relatively compactand may be used in a hospital setting or with ambulatory patients.

A further advantage of the present invention is that it allows the userto accurately and consistently mount the fluid delivery set about therotor of the present invention.

A further advantage of the present invention is that it allows the userto visually observe the flow of fluid through the fluid delivery set.

A further advantage of the present invention is that the rotor isprotected by a rotor shield which is mounted on the housing assembly.

A further advantage of the present invention is that the relativelycompact peristaltic pump is readily mountable on an aestheticallyattractive charge unit.

Further objects and advantages of the present invention are describedhereinafter and will become apparent by reviewing the drawings anddetailed description of the preferred embodiment as set forth herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective elevational view of the housingassembly; swing arm; rotor; fluid delivery set and rotor shield; of thepresent invention with the drip chamber yoke removed;

FIG. 2 is a frontal elevational view of the assembled peristaltic pumpin accordance with the present invention having the swing arm in theclosed position;

FIG. 3 is a side elevational view of the peristaltic pump in accordancewith the present invention having the swing arm in the closed position;

FIG. 4 is a side elevational view of the peristaltic pump in accordancewith the present invention having the swing arm in the open position;

FIG. 5 is a side elevational view of the peristaltic pump as shown inFIG. 4 and including a fluid delivery set loaded operationally mountedon the peristaltic pump in accordance with present invention;

FIG. 6 is a rear elevational view, partially in cross section, of theperistaltic pump in accordance with the present invention having theswing arm in the open position and showing the motor and rotor shaft ofthe present invention;

FIG. 7 is a side elevational view of the peristaltic pump in accordancewith the present invention, as shown in FIG. 3, with the rotor shieldremoved; a fluid delivery set inserted in the peristaltic pump and theswing arm in the closed position;

FIG. 8 is an enlarged and elevational side view of the rotor shieldtaken generally along line 8--8 of FIG. 2;

FIG. 9 is a top elevational view of the peristaltic pump in accordancewith the present invention with a fluid delivery set inserted thereinand having the swing arm in the closed position;

FIG. 10 is an enlarged and elevated perspective view of the drip chamberyoke of the present invention as shown in FIG. 4;

FIG. 11 is a frontal elevational view of the charger unit of the presentinvention;

FIG. 12 is a rear elevational view of the charger unit of the presentinvention;

FIG. 13 is a frontal elevational view of the peristaltic pump mounted onthe charger unit;

FIG. 14 is a cross-sectional view of the charger unit taken along lines14--14 of FIG. 11 showing the latch member of the present invention; and

FIG. 15 is a partial cross-sectional view of the charger unit and poleclamp of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIGS. 1-10, the preferred form of the present inventionincludes a rotary type of peristaltic pump 10 particularly adapted forthe controlled delivery of enteral fluid to a patient. It should beunderstood that although the present invention is described herein withreference to a rotary type of peristaltic pump, the present invention isreadily adaptable for use with nearly any type of rotary or linear pumpwherein it is desired to deliver a fluid at a controlled rate through atubular member that is mounted along at least a portion of the pump.

The peristaltic pump 10 of the present invention consists generally of arectangularly-shaped housing assembly 12 having a swing arm 16 pivotallymounted on the lower side surface thereof. The swing arm 16 includescarrying a motor 18 and partially enclosed rotor 14 mounted thereon asdescribed hereinafter. As shown in FIGS. 1 and 2, the front surface 20of the housing assembly 12 is a generally flat and rectangularly-shapedsurface which includes a control panel section 22 and an alpha numericLED display section 24. The right side of the front surface 20 includesan outwardly extending elongate upper flange 26 which extends downwardlyfrom the top portion of the front surface 20 along approximatelyone-fourth of the length of the housing assembly 12 to shield the topportion of the drip chamber assembly 42, as described more fullyhereinafter. An elongate lower flange 28 extends outwardly alongapproximately one-fourth of the length of the housing assembly 12 nearthe approximate mid section of the housing assembly 12 to position thelower section of the drip chamber assembly 42 and a first portion of thesilicone tube 44 of the fluid delivery set 40 as described more fullyhereinafter. A first opening 30 is located between the upper flange 26and the lower flange 28 to allow the user to observe the flow of fluidin the drip chamber assembly 42 during operation of the peristaltic pump10. A second opening 32 is located beneath the lower flange 28 on theright side of the housing assembly 12 to allow the user to observe theoperation of the rotor 14 of the present invention.

As described briefly above, the peristaltic pump 10 of the preferredembodiment is particularly designed for use with a conventional fluiddelivery set 40 as disclosed in U.S. Pat. No. 4,913,703, which isincorporated herein by reference. The conventional fluid delivery set 40allows medical fluid to flow therethrough and generally consists of anelongate and flexible inlet tube 45 which is connected to a source offluid (not shown) at one end and the top of the drip chamber assembly 42at the other end. The drip chamber assembly 42 preferably consists of asemi-rigid and cylindrically-shaped tapered member 46 having a top capmember 47 attached to the top end thereof. An annular rim 50 is formedas part of the cap member 47 and is located along the top surface of thetapered member 46. a top tubular member 48 extends downwardly from thecap member 47 into the interior of the drip chamber assembly 42. A lowertubular member 52 is centrally positioned on the bottom end 53 of thetapered member 46 to extend downwardly therefrom. The lower tubularmember 52 on the drip chamber assembly 42 is connected to the first endof the silicone tube 44. The silicone tube 44 preferably consists of apredetermined length of resilient and compressible silicone tubinghaving a first predetermined internal diameter in the relaxed conditionand a second predetermined internal diameter in the stretched conditionas described hereinafter. The second end of the silicone tube 44 isconnected to a circular mounting or connector member 54 which includestop and bottom tubular members, 56 and 58 respectively, which extendupwardly and downwardly therefrom and an enlarged annular flange 60which is positioned between the top and bottom tubular members, 56 and58. In the preferred form of the present invention, the annular flange60 includes a cylindrically-shaped magnet 62 thereon, the function ofwhich is described more fully hereinafter. The magnet 62 may be obtainedfrom a variety of sources; however, it has been found that a materialcomposed of 88% strontium ferrite is particularly suitable for use inthe present invention. This material includes 12% of #6 nylon and isavailable from Tengam Inc. of Otsego, Mich. The magnet 62 is magnetizedin the axial direction to a magnetic strength of approximately 400 to500 gauss at the circumferential surface. An elongate outlet tube 64includes a first end which is connected to the top tubular member 56 ofthe mounting member 54 and a second end (not shown) which is adapted todeliver the medical fluid to the patient.

As best shown in FIGS. 4-6, the upper flange 26 on the side surface ofthe housing assembly includes a semi-circularly-shaped top lip 34 whichextends rearwardly and inwardly from the top of the upper flange 26. Thetop lip 34 is shaped to protect the inlet tube 35 near the top tubularmember 48 of the drip chamber assembly 42 and assist in the loading ofthe drip chamber assembly 42 onto the peristaltic pump 10 when the fluiddelivery set 40 is mounted on the peristaltic pump 10 as describedhereinafter. The upper flange 26 includes an elongate and semi-circulardrip chamber yoke retaining flange 36 which consists of a set of flangesand recesses which are located rearwardly of the front surface 20 of theupper flange 26 to retain the drip chamber yoke 37 in fluid tightcommunication with the housing assembly 12 to allow the user to cleanthe drip chamber recess 39 without exposing the electronics in thehousing assembly 12 to the cleaning fluid. The retaining flange 36 ispositioned on the upper flange 26 to locate the drip chamber yoke 37adjacent to the drop forming bottom end of the top tubular member 48 onthe drip chamber assembly 42 as described hereinafter. A generallyrectangularly-shaped tube retaining flange 38 extends rearwardly fromthe outer surface of the yoke retaining flange 36. The tube retainingflange 38 is oriented in a spaced apart relationship with the housingassembly 12 to retain a portion of the outlet tube 64 from the fluiddelivery set 40 adjacent thereto when the swing arm 16 is in the closedposition as described hereinafter. A locking lip 35 is positionedrearwardly of the yoke retaining flange 36 and is oriented to extendperpendicular to and upwardly from the tube retaining flange 38. Thelocking lip 35 is adapted to receive a complementary locking lip 66 onthe swing arm 16 therein. The locking lip 35 on the housing assembly 12and the locking lip 66 on the swing arm 16 may be replaced by nearly anytype of positive latch including the type of latch mechanism having oneor more magnets thereon to ensure retention of the swing arm 16 in theclosed position as described hereinafter.

As shown in FIGS. 4 and 10, the drip chamber yoke 37 of the presentinvention is a rigid and generally rectangularly-shaped member having adrip chamber receiving recess 39 along the interior surface thereof. Thetop of the receiving recess 39 includes an enlarged and generally oblongshoulder area 41 which is adapted to receive the relatively rigidannular rim 50 of the drip chamber assembly 42 thereon as describedhereinafter. The internal surface of the receiving recess 39 below theshoulder area 41 is semi-circularly-shaped with a radius ofapproximately 240° to retain the drip chamber assembly 42 centeredtherein and to decrease the likelihood that the drip chamber assembly 42will be inadvertently pulled from the optimal vertical alignment in thereceiving recess 39 during operation of the present invention. Thelengthwise dimension of the receiving recess 39 forms an angular recesswhich gradually tapers inwardly to conform to the shape of the taperedmember 46 of the drip chamber 42. As shown in FIG. 10, two opposinglyoriented pairs of openings 43 are located in the side walls of the dripchamber yoke 37. The openings 43 are designed to house at least one setof drop sensing emitters and detectors (not shown). The drop sensingemitters and detectors are aligned to form an optical path which detectsdrops of fluid immediately after they fall from the bottom end of thetop tubular member 48 in the drip chamber assembly 42.

If the emitters and detectors are positioned too high with respect tothe bottom end of the top tubular member 48, The optical path may bealigned with the bottom end of the top tubular member 48. In thissituation, the peristaltic pump 10 may not detect the formation of dropsin the drip chamber assembly 42 and the motor 18 of the peristaltic pump10 will stop operating and indicate to the operator that there is a flowerror. If the emitters and detectors are positioned too low with respectto the bottom end of the top tubular member 48, the peristaltic pump 10may not detect the drops of medical fluid because the lower portion ofthe tapered member 46 may become coated with enteral fluid due to thesplashing of the drops as they fall in the drip chamber assembly 42. Inthis situation, the peristaltic pump 10 will then stop operating andindicate to the user that there is a flow error because the fluid dropsare not being sensed by the emitters and detectors.

Finally, if the emitters and detectors are not optimally positioned withrespect to the bottom end of the top tubular member 48, the user mayalso experience a flow error alarm if the peristaltic pump 10 is tiltedso that the drops in the drip chamber assembly 42 do not fall throughthe optical path of the emitters and detectors. If the emitters anddetectors are positioned too far below the bottom end of the top tubularmember 48 and the peristaltic pump 10 is not maintained in a verticalposition, the falling drops of medical fluid may not pass through theoptical path of the emitters and detectors and the peristaltic pump 10will discontinue operating and indicate to the user that there is a flowerror. When the present invention is used as an ambulatory infusiondevice, it is much more likely that the peristaltic pump 10 will beoperated in a position which is not completely vertical and thereforethe incidence of flow error alarms due to the failure of the emittersand detectors to detect the falling drops will likewise increase.Therefore, as described hereinafter, the drip chamber yoke 37 of thepresent invention is designed to ensure that the bottom end of the toptubular member 48 is optimally positioned adjacent to the optical pathcreated by the emitters and detectors.

As discussed briefly above, the length of the drip chamber assembly 42may also vary between individual fluid delivery sets 40. In priorperistaltic pumps, the drip chamber assembly is retained in position onthe peristaltic pump by inserting the bottom end of the drip chamberassembly into a first recess on the housing assembly and there isnothing to ensure that the bottom end of the top tubular member in thedrip chamber assembly 42 is optimally positioned so that the drop willpass through the optical path. Because the fluid delivery set 40 ischanged everyday, the present invention is designed to accommodatevariations in the length of drip chamber assemblies 42 without adverselyaffecting the drop sensing operation of the peristaltic pump 10 byensuring that the emitters and detectors are optimally positioned withrespect to the bottom end of the top tubular member 48 while notadversely affecting the distance the silicone tube 44 is stretched aboutthe rotor 14. The drip chamber assembly 42 of the preferred fluiddelivery set 40 has a nominal length of 2.5075 inches and cumulativedimensional tolerance of ±0.035 inches. The drip chamber yoke 37 of thepresent invention allows the bottom end 53 of fluid delivery sets 40which have a longer drip chamber assembly 42 to rest on the firstmounting recess 68 so that a minimal amount of the top end of the dripchamber assembly 42 will extend above the shoulder area 41 of the dripchamber yoke 37 and the optical path of the emitters and detectors willbe only slightly below the optimal position with respect to the bottomend of the top tubular member 48. The fluid delivery sets 40 which havea the shorter drip chamber assembly 42 will be supported in the dripchamber yoke 37 by contact between the annular rim 50 of the dripchamber assembly 42 in the shoulder area 41 of the receiving recess 39so that the bottom end of the top tubular member 48 will be optimallypositioned with respect to the optical path of the emitters anddetectors. When the shorter drip chamber assembly 42 is supported by theshoulder area 41 in the drip chamber yoke 37, the silicone tube 44 maybe stretched slightly more than when the bottom end 53 of the dripchamber assembly 42 is supported in the first mounting recess 68;however, because the stretching of the silicone tube 44 is distributedover the entire length of the silicone tube 44, the internal diameter ofthe silicone tube 44 is not significantly affected and the amount ofenteral fluid delivered by each rotation of the rotor 14 on theperistaltic pump 10 is not adversely affected.

As shown in FIG. 4, an oblong and generally semicircular first mountingrecess 68 is positioned behind the front surface of the lower flange 28and slightly below the top surface thereof. The first mounting recess 68includes a grooved shoulder area 69 which is sized to receive the bottomend 53 of the drip chamber assembly 42 therein while allowing the lowertubular member 52 of the drip chamber assembly 42 to extendtherethrough. A first set loading channel 70 extends downwardly from thefirst mounting recess 68 to the top end of the second opening 32 whichbegins slightly below the top of the rotor 14. A raised frictionaldetent 71 is located beneath the lower flange 28 near the front surfaceof the housing assembly 12 to releasably retain the swing arm 12 in theopen position as described hereinafter.

As shown in FIG. 1, the rotor 14 of the present invention is acylindrical member having inner and outer enlarged flanges 72 and 74,respectively. As described above, the rotor is designed to extend fromthe side surface of the housing assembly 12. The enlarged flanges, 72and 74, include three equally spaced rollers 76 extending therebetweenalong the circumference of the rotor 14. The rollers 76 are mounted onmetal pins which extend between the inner and outer enlarged flanges 72and 74 so that the rollers 76 rotate freely when they are placed incontact with the silicone tube 44 of the fluid delivery set 40 asdescribed hereinafter. The rotor 14 is mounted on an inwardly directedcentral shaft 78 (FIG. 6) which extends from the inner enlarged flange72 to the motor 18 so that the rotational forces created by the motor 18are transferred directly to the rotor 14. A circular recess 80 islocated on the central axis of the rotor 14 along the outer surface ofthe outer enlarged flange 74, the function of which is describedhereinafter.

The interior of the housing assembly 12 includes the electroniccircuitry (not shown) of the peristaltic pump 10 and a pair of annulargrooves 82 located inwardly from the rotor 14 as shown in FIG. 1. Theswing arm 16 of the present invention includes a hollow andcylindrically-shaped bearing sleeve 84 which extends inwardly from theside surface of the housing assembly 12. The motor 18 of the presentinvention is frictionally retained in the bearing sleeve 84 so that themotor 18 rotates as the swing arm 16 is rotated between the open andclosed positions. The external surface of the bearing sleeve 84 includesa pair of inner and outer circular flanges 85 and 86, respectively,which are received in the annular grooves 82 on the housing assembly 12to allow rotational movement of the swing arm 16 while preventinglongitudinal movement of the swing arm 16 and motor 18 with respect tothe housing assembly 12. The outer circular flange 86 includes anoutwardly directed lip 88 which encircles the circumference of the innerflange 72 on the rotor 14. The bottom of the lip 88 is positionedslightly inwardly from the outer surface of the inner flange 72 andincreases in outward extension from the bottom of the rotor 14 to thetop of the rotor 14 wherein the lip 88 extends outwardly from the outersurface of the inner flange 72 to assist in the placement of thesilicone tube 44 around the rotor 14 as described hereinafter.

As shown in FIG. 4, a second set loading channel 90 is formed along thelengthwise dimension of the swing arm 16 by first and second wallmembers, 92 and 94 which extend outwardly from the inner surface of theswing arm 16. As shown in FIGS. 5, 7 and 9, the second set loadingchannel 90 is generally U-shaped and includes a top semi-circularopening 96 through which the outlet tube 64 of the fluid delivery set 40extends. A pair of inwardly directed ridges 98 are positioned slightlybelow the top surface 116 of the swing arm 16. The ridges 98 extendinwardly approximately two thirds of the way into the second set loadingchannel 90 so that the exterior portion of this area of the second setloading channel 90 is narrower than the interior portion of this sectionof the loading channel 90. The width of the exterior surface of thesecond set loading channel 90 gradually increases from the ridges 98near the top surface 116 of the swing arm 16 to a location approximatelyone-fourth of the distance along the swing arm 16 to a lower enlargedwidth area defined herein as the mounting member receiving section 110of the second set loading channel 90. The receiving section 110 of thesecond set loading channel 90 is an elongate and generallyrectangularly-shaped recess in the swing arm 16. The receiving section110 is sized to conveniently receive the mounting member 54 and thesecond end of the silicone tube 44 of the fluid delivery set 40 therein.The bottom end of the receiving section 110 is aligned with a lowersilicone tube channel 115 which forms the lower section of the secondset loading channel 90. The top end of the silicone tube channel 115includes a semi-circular and reduced width second mounting recess 112which forms a shoulder area 111 in the second set loading channel 90.The shoulder area 111 is adapted to receive the bottom of the mountingmember 54 thereon as described hereinafter. The silicone tube channel115 includes a gradually tapered section 113 on the second wall member94 which tapers rearwardly and downwardly along the swing arm 16 toincrease the width of the second set loading channel 90 from a locationbelow the second mounting recess 112 to the bottom of the second wallmember 94. The second wall member 94 is designed to end below the top ofthe rotor 14 while the first wall member 92 extends generally linearlydownwardly from the second mounting recess 112 to a location adjacentthe top of the rotor 14 when the swing arm 16 is in the closed positionas described hereinafter.

As shown in FIG. 4, the inner surface of the second set loading channel90 includes a sensor opening 114 located immediately above and adjacentto the second mounting recess 112 to allow a magnetic sensor 117 tosense when the mounting member 54 is inserted in the swing arm 16 andthe swing arm 16 is moved to the closed position as describedhereinafter. The magnetic sensor 117 of the present invention ispreferably a magneto resistive switching element, such as part No.SS21PE available from Microswitch Inc. of Freeport, Ill. which isdesigned to provide an output of plus 5 volts when not in the presenceof a magnetic field and zero volts when in the presence of eitherpolarity of a magnetic field such as the magnetic field created bymagnet 62. The inner surface of the swing arm 16 also includes secondopening 118 located below the top surface 116 of the swing arm 16 andabove the receiving section 110 of the second set loading channel 90.The second opening 118 is sized to receive the retaining flange 38 ofthe housing assembly 12 therethrough when the swing arm 16 is in theclosed position. As shown in FIG. 6, the top surface 116 of the swingarm 16 includes a locking lip 66 extending downwardly and linearly alongthe inner surface of the top surface 116 so that the locking lip 66contacts the locking lip 39 on the housing assembly 12 to releasablyretain swing arm 16 in the closed position. The top of the swing arm 16also includes a flat and generally rectangularly shaped drip chambershade 120 (FIGS. 4 and 5) which is designed to protect the emitters anddetectors in the drip chamber yoke 37 and the top of the drip chamberassembly 42 from interference by ambient light when the swing arm 16 isin the closed position as described hereinafter.

As shown in FIGS. 1 and 8, the preferred embodiment of the presentinvention includes a rotor shield 122 to facilitate the loading of thefluid delivery set 40 around the rotor 14 and to protect the rotor 14and shaft 78 from accidental damage caused by contact with the rotor 14during movement of the peristaltic pump 10. The rotor shield 122includes a mounting surface 123 which is attachable to the side surfaceof the housing assembly 12 at a location on the housing assembly 12which is oriented rearwardly from the lower flange 28. The rotor shield122 is designed to be removable from the housing assembly 12 so that therotor 14 and rotor shield 122 may be cleaned without exposing theelectronics in the housing assembly 12 to the cleaning fluid. Themounting surface 123 extends outwardly therefrom to a generally planarportion of the rotor shield 122 which is generally aligned with theouter surface of the swing arm 16. The planar surface of the rotorshield 122 consists generally of a flat and rectangularly-shaped uppersection 125 and an oblong-shaped lower section 127. The upper section125 and the lower section 127 of the rotor shield 122 are positionedalong the side surface of the housing assembly 12 to extend downwardlyfrom the lower flange 28 and along the side surface of the housingassembly 12 to a location spaced outwardly from the outer flange 74 ofthe rotor 14.

As shown in FIG. 8, the inner surface of the rotor shield 122 near thetop of the upper section 125 includes an inwardly directed and generallylinear top flange 124 which extends inwardly from the rotor shield 122to a location adjacent to the top of the second mounting recess 112 onthe swing arm 16 when the swing arm 16 is in the closed position. Thetop flange 124 and the second mounting recess 112 form a generallyclosed recess having a closed section only slightly larger than thediameter of the mounting member 54. The top of the top flange 124 alsoincludes a chamfer thereon to facilitate the movement of the mountingmember 54 into the second mounting recess 112 as the swing arm 16 ismoved to the closed position as described hereinafter. An elongate andgenerally L-shaped intermediate flange 126 extends inwardly from theapproximate intersection of the upper section 125 and lower section 127of the rotor shield 122. The intermediate flange 126 extends inwardlyfrom the rotor shield 122 to a location which is adjacent to the top ofthe rotor 14 and extends inwardly of the outer flange 74 of the rotor14. The rear end 128 of the intermediate flange 126 is oriented at anangle of approximately 65° from the main portion thereof and extendsdownwardly therefrom to a location adjacent to the tapered section 113on the second wall member 94 of the swing arm 16 when the swing arm 16is in the closed position.

As shown in FIG. 8, a centrally positioned set of stiffening ribs 130extend inwardly from the center of the lower section 127 of the rotorshield 122. The ribs 130 preferably include four laterally extendingarms which are designed to be normally spaced apart from the circularrecess 80 located on the outer flange 74 of the rotor 14. The ribs 130are designed to reduce the bending forces applies to the lower section127 of the rotor shield 122 when an external force is applied to therotor shield 122. Additionally, a circular protrusion 132 extendsinwardly from the center of the ribs 130. The orientation of the ribs130 with respect to the circular recess 80 decreases the likelihood thatthe shaft 78 of the rotor 14 will be bent or damaged by contact betweenthe side of the peristaltic pump 10 or rotor 14 and an external object.The circular protrusion 132 is aligned with the axial center of therotor 14 and allows the rotor 14 to continue rotating with only a slightincrease in resistance to rotation when the side of the peristaltic pump10 rests against an object. Therefore, the operation of the motor 14 ofthe present invention will not be significantly affected by moderatecontact with an external object against the side of the peristaltic pump10 of the type which may occur during ambulatory use. The bottom edge ofthe rotor shield 122 includes an inwardly directed bottom flange 134which has an apex 136 thereon located approximately midway along thelengthwise dimension of the bottom flange 134. The apex 136 preferablyextends inwardly from the rotor shield 132 to a location adjacent to theinner surface of the outer flange 74 on the rotor 14 and is designed toguide the fluid delivery set 40 toward the center of the rollers 76 onthe rotor 14 on those occasions when the fluid delivery set 40 is notloaded completely flat in the first and second set loading channels 70and 90, as described hereinafter.

The installation of the fluid delivery set 40 on the peristaltic pump 10of the present invention is reltively simple and the likelihood that thefluid delivery set 40 will be improperly mounted on the peristaltic pump10 is significantly reduced as compared to currently availableperistaltic pumps. Initially, the swing arm 16 is rotated to the open orloading position so that the inner surface of the swing arm 16 contactsthe frictional detent 71 as shown in FIG. 4. In this open position, thedrip chamber receiving recess 39; the first mounting recess 68; thefirst set loading channel 70 on the housing assembly 12 and the entiresecond set loading channel 90 on the swing arm 16 are exposed to allowfor the insertion of the fluid delivery set 40 therein. Initially, thedrip chamber assembly 42 of the fluid delivery set 40 is placed on thehousing assembly 12 by inserting the annular rim 50 of the drip chamberassembly 42 below the top lip 34 of the housing assembly 12 so that thebottom end 53 of the drip chamber assembly 42 is positioned above thefirst mounting recess 68. The mounting member 54 is then inserted intothe receiving section 110 of the second set loading channel 90 on theswing arm 16 such that the silicone tube 44 is loosely positioned nearthe front surface of the rotor 14. Finally, the outlet tube 64 is pulledinwardly between the ridges 98 into the wider interior of the second setloading channel 90 on the swing arm 16. The width of the silicone tubechannel 115 and the semi-circular opening 96 are sized so that themounting member 54 will only fit in the receiving section 110 of thesecond set loading channel 90. Additionally, the second set loadingchannel 90 on the swing arm 16 is sized so that it will not accept thedrip chamber assembly 42 therein and therefore, the user cannotaccidentally reverse the drip chamber assembly 42 and mounting member 54while loading the fluid delivery set 40 on the present invention.

The swing arm 16 of the present invention is particularly designed sothat the swing arm 16 rotates generally about the axial center of therotor 14 from the open position (FIGS. 4, 5 and 6) to the closedposition (FIGS. 2, 3 and 7). The orientation of the swing arm 16 aboutthe axial center of the rotor increases the relative distance betweenthe first mounting recess 68 on the housing assembly 12 and the secondmounting recess 112 on the swing arm 16 through the first set loadingchannel 70 and the silicone tube channel 115 as the swing arm 16 ismoved from the open position to the closed position. Once the fluiddelivery set 40 has been inserted in the housing assembly 12 and swingarm 16 as described above, the silicone tube 44 of the fluid deliveryset 40 will remain in the relaxed and unstretched condition near thefront of the rotor 14 until the swing arm 16 is rotated to a positiongenerally perpendicular to the rear surface of the peristaltic pump 10.As the swing arm 16 reaches this position, the silicone tube 44 willcontact the rollers 76 on the rotor 14. As described above, if thesilicone tube 44 is not initially aligned near the rollers 76 on therotor 14, the silicone tube 44 will contact the bottom flange 134 on therotor shield 122 and slide inwardly as the swing arm 16 is rotated sothat the silicone tube 44 is properly positioned about the rollers 76 onthe rotor 14. Continued rotation of the swing arm 16 will cause themounting member 54 to be drawn downwardly in the receiving section 110of the loading channel 90 until the bottom surface of the mountingmember 54 is positioned inwardly of the top flange 134 on the rotorshield 122 to contact the shoulder area 111 in the top of the secondmounting recess 112. Additionally, as described above, the drip chamberassembly 42 will be pulled downwardly in the drip chamber receivingrecess 39 until the annular rim 50 of the drip chamber assembly 42contacts the shoulder area 41 in the drip chamber yoke 37 or until thebottom end 53 of the tapered member 46 contacts the shoulder area 69 inthe top of the first mounting recess 68. Continued rotation of the swingarm 16 causes the silicone tube 44 to be stretched and compressed aroundthe rollers 76 on the rotor 14. When the swing arm 16 is rotated to theclosed position as shown in FIGS. 2 and 3, the locking lip 66 on theswing arm 16 will contact the locking lip 35 on the housing assembly 12so that the swing arm 16 will be frictionally retained in the closedposition.

When the swing arm 16 is in the closed position as shown in FIG. 7, theinlet tube 45 extends through an opening in the top surface of thehousing assembly 12 formed by adjacent semi-circular edges of the swingarm 16 and the top lip 34 of the upper flange 26 (FIG. 9). The bottomend of the top tubular member 48 of the drip chamber assembly 42 ispositioned slightly above the optical path of the emitters and detectorsin the drip chamber yoke 37 so that the falling drops of fluid may besensed by the emitters and detectors. As described above, the dripchamber shield 120 encloses the outer side of the top portion of thedrip chamber assembly 42 to prevent ambient light from interfering withthe operation of the emitters and detectors and to assist in retainingthe tapered member of the drip chamber assembly 42 in the receivingrecess 39 of the drip chamber yoke 37. The bottom end 53 of the dripchamber assembly 42 is positioned in the shoulder area 41 of the firstmounting recess 68.

The silicone tube 44 is connected to the lower tubular member 52 of thedrip chamber assembly 42 and extends downwardly from the first mountingrecess 68 and through the first set loading tube channel 70 to contactone or more rollers 76 on the rotor 14. The silicone tube 44 iscompressed around the rollers 76 so that a predetermined quantity offluid is trapped between the spaced apart rollers 76. The silicone tube44 also extends upwardly from the rotor 14 and passes rearwardly of theintermediate flange 126 on the rotor shield 122. The silicone tube 44then extends through the silicone tube channel 115 to the secondmounting recess 112. The stretching of the silicone tube 44 causes themounting member 54 to seat in the shoulder area 111 in the secondmounting recess 112 and behind the top flange 124 of the rotor shield122 so that the magnet 62 on the annular flange 60 is positionedadjacent the sensor opening 114 in the swing arm 16. The positioning ofthe magnet 62 adjacent to the sensor opening 114 allows the magneticsensor 117 in the housing assembly 12 to sense the presence of themagnet 62 and enable the operation of the motor 18 when the magnet 62 issensed.

The outlet tube 64 of the fluid delivery set 40 extends upwardly throughthe receiving section 110 of the second set loading channel 90 andpasses behind the retaining flange 38 on the housing assembly 12 and theridges 98 on the swing arm 16. In prior peristaltic pumps, the outlettube 64 would oftentimes be pinched at the connection of the outlet tube64 and the top tubular member 56 of the mounting member 54 if thepatient or the peristaltic pump were moved. This caused an increase inthe back pressure in the silicone tube 44 so that the rollers 76 do notproperly close or compress the silicone tube 44. In peristaltic pumps,the amount of fluid actually delivered to the patient through the fluiddelivery set 40 by the peristaltic pump 10 decreases as the backpressure in the silicone tube 44 increases. Therefore, the outlet tube64 in the present invention is designed to extend through the second setloading channel 90 as described above to prevent the outlet tube 64 frombeing pinched at the connection of the outlet tube 64 and the toptubular member 56 on the mounting member 54. Additionally, the sides ofthe second set loading channel 90 at the top surface 116 of the swingarm 16 are chamfered to decrease the likelihood that the flow of fluidwill be impaired by pinching the outlet tube 64 against the swing arm16.

The present invention also includes a number of other features which aredesigned to prevent the swing arm from closing if the fluid delivery set40 is improperly positioned in the housing assembly 12 and the swing arm16. If the user inserts the mounting member 54 into the silicone tubechannel 115 rather than in the receiving section 110, the rear end 128of the intermediate flange 126 and the tapering section 113 of thesecond wall member channel 94 will push the circular mounting member 54downwardly from the silicone tube channel 115 so that it will be visiblealong rear surface of the rotor and the magnet 62 will not be sensed bythe magnetic sensor 177 to prevent the motor 18 from operating. If theuser fails to properly place the outlet tube 64 behind the ridges 98 onthe top of the swing arm 16, the outlet tube 64 will be pinched againstthe second wall member 94 of the swing arm 16 by the retaining flange 38in the housing assembly 12 so that fluid flow will be restricted throughthe outlet tube 64. If the user places the silicone tube 44 in front ofthe rotor shield 122 rather than behind it, the silicone tube 44 will bepinched between the rear end 128 of the intermediate flange on the rotorshield 122 and the tapering section 113 on the second wall member 94.Finally, as described above, the receiving section 110 of the loadingchannel 90 is sized so that the user cannot inadvertently load the dripchamber assembly 42 in the receiving section 110 of the second setloading channel 90 because the drip chamber assembly 42 is too large tofit in the receiving section 110 of the second set loading channel 90.

As shown in FIGS. 11-15, the present invention also includes a chargerunit 150 which is adapted to releasably receive the peristaltic pump 10thereon. The charger unit 150 generally includes a base member 152 whichis sized to slidably receive the bottom of the housing assembly 12therein and an upwardly extending and generally rectangularly-shapedcharger unit body member 154. As shown in FIG. 11, the base member 152extends forwardly of the lower surface of the body member 154 andincludes an upwardly extending forward lip 156 on the front surfacethereof. A forwardly extending side lip 158 extends upwardly along theleft side of the base member 152 and forwardly projects from the bodymember 154 to receive the front surface 20 of the housing assembly 12therebehind. A latch opening 160 is located on the top surface of thebase member 152 near the back of the base member 152 and adjacent to theside lip 158. Additionally, as shown in FIG. 14, a latch release opening161 is located along the outer surface of the lower portion of the sidelip 158.

The front surface of the body member 154 includes an elongate andgenerally rectangular slide member 162 which extends forwardly from thebody member 154 a short distance below the approximate midpoint of thebody member 154. As shown in FIG. 11, the slide member 154 extendshorizontally from the intersection of the body member 154 and the sidelip 158 to a rounded second end which is located near the opposite sideof the body member 154. A conductive array of contact members 164 areoriented generally perpendicular to the slide member 162 and extendforwardly from the body member 154 along the intersection of the bodymember 154 and the side lip 158 below the slide member 162.

As shown in FIG. 12, the rear surface of the body member 154 includes alower semicircular support pole receiving surface 166 and a generallyT-shaped pole clamp 168. The receiving surface 166 is positioned on thesame side of the body member 154 as the side lip 158 and extendsupwardly along the rear surface of the body member 154 approximatelytwo-thirds of the distance along the member 154. The pole clamp 168includes an elongate and horizontally oriented leg member 170 having aleaf spring retaining recess 171 therein; a threaded shaft member 172extending therethrough and a vertically oriented clamping member 174having a semi-circular recess on its interior surface. As shown in FIG.15, the retaining recess 171 includes an outwardly biased leaf spring173 which includes a first leg retained in the retaining recess 171 anda second leg which is biased against the rear surface of the chargerunit 150.

As shown in FIG. 14, an elongate and semi-rigid latch member 176 isenclosed in a latch channel 178 located along the bottom surface of thebase member 152. The latch member 176 is oriented generally parallel tothe forward lip 156 and is positioned rearwardly thereof in the latchchannel 178 located in the base member 152. The right side of the latchmember 176 includes a mounting surface 180 which is adapted to befixedly mounted to the bottom surface of the base member 152 near theright side of the latch channel 178. A raised retaining member 182extends upwardly from the latch member 176 to extend through the latchopening 160 on the top surface of the base member 152. In the presentinvention, the retaining member 182 includes a gradually upwardlysloping first surface which is nearest to the mounting surface 180 and asecond surface which is oriented generally perpendicular to the bottomsurface of the base member 152. A latch release member 183 extendsupwardly from the left side of the latch member 176 to extend throughthe release opening 161 located on the outer surface of the side lip158.

When the user desires to recharge the peristaltic pump 10; operate theperistaltic pump 10 with an external power source (not shown) or supportthe peristaltic pump 10 on a support pole 190, the peristaltic pump 10is initially aligned with the right side of the charger unit 150 so thatthe elongate slide recess 184 (FIG. 6) on the rear surface of thehousing assembly 12 is aligned with the slide member 162 on the forwardsurface of the body member 154. As the peristaltic pump 10 is moved tothe left, the slide member 162 will align the contact members 164 on thecharger unit 150 with contact members 186 (FIG. 6) on the rear sidesurface of the housing assembly 12 opposite the rotor 14. Once theperistaltic pump 10 reaches the side lip 158, the retaining member 182on the latch member 176 will contact and enter the latch recess 188(FIG. 6) on the bottom surface of the housing assembly 12 to releasablyretain the peristaltic pump 10 on the charger unit 150. When theperistaltic pump 10 is retained in this position, the contact members164 on the charger unit will be aligned with and in operative contactwith the contact members 186 on the housing assembly 12 to allow thecharger unit 150 to charge the batteries (not shown) and provideoperating power to the peristaltic pump 10. When the batteries of theperistaltic pump 10 have been charged, the user may release theperistaltic pump 10 from the charger unit 150 by depressing the releasemember 183 on the outer surface of the side lip 158. When the releasemember 183 is depressed, the retaining member 182 is biased downwardlyin the channel 178 so that the retaining member 182 is released from thelatch recess 188 on the bottom surface of the housing assembly 12. Theperistaltic pump 10 may then be moved to the right and removed from thecharger unit 150.

If the user desires to mount the peristaltic pump 10 to the support pole190, the peristaltic pump 10 is initially inserted into the charger unit150 as described above. The shaft member 172 on the pole clamp 168 isthen unthreaded to allow the support pole to be inserted between theclamping member 174 and the rear surface of the body member 154 so thatthe support pole is aligned in the receiving surface 166 on the bodymember 154 and in compressive contact with a flexible pole receivingflange 189 on the inner surface of the clamping member 174. As shown inFIG. 15, the receiving flange 189 includes an interiorly directedflexible edge or bumper which is particularly designed to be compressedagainst the support pole 190 to frictionally retain the peristaltic pump10 and charger unit 150 in position on the support pole 190. In thisposition, the leaf spring 173 pivotally biases the clamping member 174outwardly from the rear surface of the body member 154 so that the rightend of the leg member 170 pivotally maintains contact with the rearsurface of the body member 154. As the connector 172 is threadedinwardly, the pole clamp 168 pivotally contacts the support pole 190 sothat the receiving flange 189 of the clamping member 174 pivotallypresses the support pole 190 against the rear surface of the body member154 in the receiving surface 166 and the leg member 170 contacts therear surface of the body member 154. As shown in FIG. 13, the swing arm16 of the present invention is fully operational when the peristalticpump 10 is mounted on the charger unit 150 and when the combination ismounted on a support pole 190.

What is claimed is:
 1. A drip chamber yoke assembly for retaining drip chamber assembly of a fluid delivery set in proper alignment with the drop sensing elements of a peristaltic pump, the drip chamber yoke assembly comprising:a body member having top and bottom and side surfaces and a downwardly extending drip chamber receiving first recess therein; a shoulder area operatively associated with said body member wherein said shoulder area is sized to receive an annular rim located near the top of a drip chamber assembly therein; and a mounting member including a second recess therein, said second recess including a shoulder surface thereon and wherein said mounting member is spaced a predetermined distance below said body member such that when the length of the drip chamber assembly exceeds said predetermined distance, the bottom of the drip chamber assembly rests on said mounting member and when the length of the drip chamber assembly is less than said predetermined distance, the annular rim of the drip chamber assembly rests adjacent said shoulder area of said body member and the bottom of the drip chamber assembly is spaced apart from said shoulder surface of said second recess.
 2. The drip chamber yoke assembly of claim 1 wherein a portion of said body member has a radius of greater than 180 degrees to retain the drip chamber assembly therein.
 3. The drip chamber yoke assembly of claim 2 wherein said first recess of said body member is tapered inwardly and downwardly and includes a radius greater than 180 degrees to retain the drip chamber assembly therein.
 4. The drip chamber yoke assembly of claim 1 wherein said body member includes drop sensing elements therein oriented to detect drops of fluid as the drops of fluid fall through the drip chamber assembly.
 5. The drip chamber yoke assembly of claim 1 wherein said shoulder area of said body member is generally oblong shaped and is positioned above said first recess of said body member.
 6. The drip chamber yoke assembly of claim 5 wherein said shoulder surface of said mounting member is positioned above said second recess and said second recess is generally semi-circular and oblong shaped.
 7. The drip chamber yoke assembly of claim 1 wherein said shoulder area of said body member is spaced apart from said shoulder surface of said mounting member such that when the length of the drip chamber assembly is less than said predetermined length, the annular rim of the drip chamber assembly is received in said shoulder area of said body member and the drip chamber assembly is spaced apart from said shoulder surface of said mounting member.
 8. The drip chamber yoke assembly of claim 7 wherein said shoulder area is spaced apart from said shoulder surface such that when the length of the drip chamber assembly is greater than said predetermined length, the drip chamber assembly is received on said shoulder surface of said mounting member and the annular rim of the drip chamber assembly is spaced apart from said shoulder surface of said body member.
 9. A fluid delivery apparatus for the controlled flow of a medical fluid through a fluid delivery set having a drip chamber assembly therein, the fluid delivery apparatus comprising:a housing assembly; a drip chamber yoke operatively extending from said housing assembly and including a first recess extending therethrough; a mounting member operatively extending from said housing assembly and positioned a predetermined distance below said yoke, said mounting member including a second recess extending therethrough and wherein said first and second recesses are sized to receive a portion of the drip chamber assembly therein; and wherein said predetermined distance between said yoke and said mounting member is chosen such that when the length of the drip chamber assembly is less than said predetermined distance, the drip chamber assembly rests on said yoke and when the length of the drip chamber assembly is greater than said predetermined distance, the drip chamber assembly rests on said mounting member.
 10. The fluid delivery apparatus of claim 9 wherein said yoke includes a drop sensing means operatively associated therewith to detect the flow of fluid as the fluid passes through the drip chamber assembly.
 11. The fluid delivery apparatus of claim 9 wherein said yoke includes a shoulder area thereon and said mounting member includes a shoulder surface thereon and the drip chamber assembly is retained on said shoulder area when the length of the drip chamber assembly is less than said predetermined distance.
 12. A fluid delivery assembly for delivering a medical fluid to a patient, the assembly comprising:a fluid delivery set including an elongate drip chamber means thereon, said drip chamber means including a top portion with a top member thereon and a bottom portion having a bottom surface thereon; a fluid delivery apparatus including a housing assembly; a first member operatively extending from said housing assembly, said first member including a first receiving means thereon; a second member operatively extending from said housing assembly, said second member including a second receiving means thereon; and said second member being spaced apart from said first member a predetermined distance such that said drip chamber means is supported on said second member when the length of said drip chamber means is greater than said predetermined distance between said first member and said second member.
 13. The fluid delivery assembly of claim 12 wherein said first member includes a sensing means therein to sense the flow of medical fluid through said fluid delivery set.
 14. The fluid delivery assembly of claim 12 wherein said first receiving means is a semi-circular recess having a radius greater than 180 degrees and said top portion of said drip chamber means is received therein.
 15. The fluid delivery assembly of claim 12 wherein said first member includes a shoulder area thereon and said top member of said drip chamber means is received thereon when the length of said drip chamber means is less than said predetermined distance.
 16. The fluid delivery assembly of claim 12 wherein said second member includes a shoulder surface thereon and said bottom surface of said drip chamber means is supported thereon when the length of said drip chamber means is greater than said predetermined distance.
 17. The fluid delivery assembly of claim 12 wherein said fluid delivery set extends through said first receiving means and said second receiving means and wherein said drip chamber means is operatively aligned with a sensing means operatively associated with said housing assembly to detect the flow of fluid through said fluid delivery set.
 18. The fluid delivery assembly of claim 17 wherein said drip chamber means is a tapered member and said first receiving means is similarly tapered and said first receiving includes at least a portion thereof has a radius greater than 180 degrees to releasably receive said top portion of said drip chamber means therein.
 19. A fluid delivery assembly for delivering medical fluid to a patient at a controlled rate, the assembly comprising:a fluid delivery set including an elongate drip chamber having a top portion with an annular top member thereon and a bottom portion with a bottom surface thereon wherein the top portion and bottom portion include tubing extending therefrom; a fluid delivery apparatus including a housing assembly with an infusion control member thereon; a first member extending from said housing assembly, said first member including a shoulder area along the top surface thereof, a first recess extending therethrough and a drop sensing means therein, said first recess having a radius greater than 180 degrees to receive said top portion of said drip chamber therein; a second member extending from said housing assembly a predetermined distance below said first member, said second member including a shoulder surface thereon and a second recess extending therethrough to removably receive a portion of said fluid delivery set therein; and said first and second members being spaced apart a predetermined distance and operatively positioned above said infusion control member on said housing assembly and wherein said top member of said drip chamber is supported by said shoulder area of said first member and said bottom surface of said drip chamber is spaced apart from said shoulder surface of said second member when the length of said drip chamber is less than said predetermined distance and said bottom surface of said drip chamber is supported by said shoulder surface of said second member when the length of said drip chamber is greater than said predetermined distance so that said drop sensing means is aligned with said top portion of said drip chamber. 